Recent morphology and sedimentary processes along the western slope of Great Bahama Bank (Bahamas)

Abstract

Carbonate slopes and associated resedimented deposits have recently gained renewed interest because they represent volumetrically significant parts of carbonate platforms. Carbonate slopes are highly variable compositionally, architecturally and spatially due to a spectrum of sediment sources, resedimentation processes and controlling factors. Here, new high resolution acoustic data (including EM302 multi‐beam echo‐sounder and very high resolution seismic) and piston cores document highly diverse and complex morphological features along the north‐western slope of Great Bahama Bank. The recent morphology of the slope is the result of the interplay between depositional and erosive processes that vary through time and along strike. The different sedimentary processes are recorded as a Pleistocene lowstand surface, characterized by many erosional features and a Holocene sedimentary wedge along the upper to middle slope that partially covers the underlying Pleistocene surface. Sedimentary processes during the Holocene are dominated by density cascading flows, which export muddy aragonitic sediment from the platform top towards the slope. Sedimentation rates, however, vary along strike due to platform top morphology combined with the variable strength of the basinal current. Reefs and islands in the Bimini area block off‐bank sediment export, and shoals and tidal deltas from Cat Cay to the south reduce the density cascading processes. Numerous small and large slope failure scars show the instability of the steep slopes of Great Bahama Bank. Bottom currents dominate the lower slope and the basin. Striations and moats are the morphological expressions of current directions, while areas of non‐deposition document strong current and concomitant removal of off‐bank transported sediment along parts of the slope, while the Santaren Drift and the drift on the north‐western edge of Great Bahama Bank act as the depositional locus for the fine‐grained sediments transported in the current.

Geomorphology of a modern carbonate slope system and associated sedimentary processes: Example of the giant Great Abaco Canyon, Bahamas

“…Changes in backscatter values correspond to variations in nature, texture and state of the sediments and/or the sea-bed morphology (Hanquiez et al, 2007(Hanquiez et al, , 2010Principaud et al, 2018) while the VHR seismic profiles reveal(s) subsurface geometry characteristics and small-scale morphology (for example, seafloor rugosity). For the acoustic facies, the categories are based on the amplitude of the reflectivity and on the patterns observed.…”

“…These classifications provide information regarding seafloor and subsurface sedimentological parameters. Studies in siliciclastic (Damuth & Hayes, 1977;Damuth, 1980;Hanquiez et al, 2007Hanquiez et al, , 2010 and carbonate environments (Mullins & Neumann, 1979;Mullins et al, 1984;Tournadour, 2015;Principaud et al, 2018) linking echofacies and lithology provide a basis for interpreting these echofacies in terms of depositional environments and allows for calibration of interpretations. The association of acoustic facies, echofacies and morphobathymetry were integrated in a general classification of sedimentary facies (Table 1).…”

“…The combined study of bathymetry, acoustic facies and echofacies compared with previous studies (Hanquiez et al, 2007(Hanquiez et al, , 2010Tournadour, 2015;Principaud et al, 2018) allowed for the definition of different domains, which are each associated with different processes (Table 1; Figs 10, 11 and 12A).…”

Characteristics of modern carbonate contourite drifts

“…From Principaud et al . (). (C) Large marginal valley between the northern Marion Platform and the elongated, separated Marion Drift (modified from Eberli et al ., ).…”

Prediction of the calcium carbonate budget in a sedimentary basin: A “source‐to‐sink” approach applied to Great Salt Lake, Utah, USA

“…Using a source‐to‐sink approach, these authors quantified the loss of carbonate sands and aragonitic muds from a shallow platform to account for the formation of these fans. The Little and Great Bahama Banks (Bahamas) also constitute an excellent natural laboratory for demonstrating bank‐to‐slope transfer of carbonates formed on the platform, transported and produced massive deep‐water carbonate sedimentary wedges (Chabaud et al, ; Fauquembergue et al, ; Mulder et al, ; Principaud et al, ; Tournadour et al, ).…”